Radioautography에 依한 細胞環 硏究에 있어서 Cincadian Rhythm의 影響에 關하여 = The Influence of Circadian Rhythm in the Cell Cylcle Studies with ^3H-thymidine Radioautography

다국어 초록 (Multilingual Abstract)

In recent years knowledge about kinetics of various cell systems was considerably increased by application of the autoradiographic method, especially through the use of ^3H-thymidine as a label of cells in DNA synthesis. Cell cycle times of intermitotic cells have been estimated for a variety of animal and some human tissues.
In such kinetic studies, the individual variations of single cells being lost in the mean value.
During cell cycle study in our laboratory, however, significant variations have been concerned with 24 hour cycles, but the difference of their cycle times have not yet been cleared up for intact tissues in the mammalians.
The purpose of the present investigation was firstly to find out if there are a diurnal variations in the number of DNA-synthesizing cells, such as hepatic cells, cardiac muscle cell and cryptal cells of small intestine. Secondary to see if there are any correlation between the proliferation rate of the different cell population and the diurnal variations.
Several results were obtained as followings;
1. In the liver cells of 17th day of gestation, and 20 day postnatal mice showed significant circadian rhythm, which was distinguished in G_2 phase and ascending slopes of 2nd cell cycle, and not in S phase.
2. In the cryptal cell population of small intestine, no influence of circadian rhythm was recognized at any experimental groups.
3. The cardiac muscle cell population in both 17th day of gestation and 20th day postnatal mouse showed circadian variations significantly which were prolonged S phase, and total generation times.
It can be concluded that only those cell population which proliferate at a slow speed and which have a low DNA synthetic index (below 10％) should be considered circadian rhythm in the autoradiographic studies.